Raleigh, N.C. — Did a former Wake County teacher murder her husband, or did she kill him in self-defense during a fight? A doctor testified Thursday that Jose Perez, 64, was in such bad health, it would have been "a real challenge" for him to physically assault his wife, Joanna Madonna.

Madonna, 48, is on trial for first-degree murder in the June 2013 death of Perez. She has admitted to killing him but claims it was in self-defense, telling investigators Perez was abusive and had a problem with drugs and alcohol.

Madonna has said her husband attacked her with a gun, but the gun went off, hitting him, and he became enraged and tried to strangle her. She says that's when she fought back.

Dr. Robert Falge, a Raleigh doctor who treated Perez, testified Thursday that Perez had numerous health problems, including diabetes, heart disease, arthritis, chronic back pain and other serious ailments. His health was so bad, Falge said, that he could barely hold a fork or walk without assistance, let alone hold a gun and take part in a fight.

"Judging by how impaired his arms were, I think it would be a real challenge to do that. I wouldn't say impossible, but a real challenge," Falge said.

Some jurors were visibly upset, covering their eyes and fanning themselves, as a medical examiner testified Thursday about how Perez was killed and showed autopsy photos of his injuries.

Dr. Lauren Scott, an associate chief medical examiner and forensic pathologist, testified that Perez suffered numerous stab wounds, including one to his neck that severed his carotid artery, one to his left chest that perforated his heart and caused bleeding in his chest cavity, and another to his right lung that caused bleeding. He also suffered a stab wound to his jaw.

Madonna's former sister-in-law also took the stand and recalled a visit with her family in South Carolina shortly before the murder. She said Madonna seemed "on edge" during that visit. She said her son gave Madonna a gun and knife because Madonna said she was afraid of someone breaking into the house.

During opening statements Tuesday, Madonna's defense attorney, Crystal Grimes, told jurors that "there was absolutely no reason for Joanna to want Jose dead. She simply wanted a divorce, and because of his actions, she had no other choice but to defend herself."

Grimes said the pair met in an alcohol recovery program and became friends first. Perez eventually left his wife for Madonna. They were married for about four years, Grimes said, before Madonna began to suspect Perez was lying, drinking and had been unfaithful.

"While he was never physically violent, he was very controlling and very jealous," Grimes said.

After a visit to family, Madonna worked up the nerve to ask her husband for a separation. He responded with threats, her defense attorney said, and that led to a scuffle.

"He had a firearm. He shot it twice. Luckily, she wasn't hurt," Grimes said.

Prosecutors say Madonna stabbed her husband a dozen times, then threw his clothes and even his wedding ring in the trash.